The company didn’t specify what information tied to people’s cards may have been compromised, and a spokeswoman declined to comment further.

Home Depot made the announcement after nearly a week-long investigation conducted with IT security firms, banking partners and the Secret Service, it said. The investigation focused on the period from April onward.

Home Depot assured customers that they won’t be held responsible for fraudulent charges and said it would provide identity protection services, including credit monitoring, to any customers who used a payment card at a Home Depot store since April.

“We apologize for the frustration and anxiety this causes our customers, and I want to thank them for their patience and support as we work through this issue,” Home Depot Chairman and CEO Frank Blake said in a statement.